A 24 GHz power amplifier with high gain and high output power based on 130 nm Comple-mentary Metal Oxide Semiconductor(CMOS) is designed. Impedance matching and power synthesis are achieved through on chip transform er coupling, which effectively promotes the matching characteristics and improves the output power of the amplifier. The simulation result shows that, under a 1.5 V power supply, the power gain is 27.2 dB; the input and output return losses are more than 10 dB; the 1dB output power compression point is 13.2 dBm with a saturated output power of 17.2 dBm; the peak Power Added Efficiency(PAE) is 13.5%.